A method of singulating a semiconductor die from a wafer is provided. The method includes etching or cutting several trenches into the wafer from a front surface of the wafer, such that each trench extends along an entire side of the die; depositing a passivation layer into the trenches to form a passivation plug on at least a bottom of the trenches to protect the dies and immobilize them during singulation; and forming a rigid carrier layer or plate at the first side of the wafer to secure the dies. The wafer is then ground from the back side to expose the bottom of each trench, a metal layer is formed on the back surface of the wafer; dicing tape is added, the carrier layer is removed, and the die is separated from the wafer by laser cutting or by flexing the tape.
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1. A method of singulating a semiconductor die from a wafer, the method comprising:
at least one of etching or cutting a plurality of trenches into the wafer from a first side of the wafer, each trench including opposite sidewalls and extending through at least a majority of a depth of the wafer along an entire side of the die;
depositing a passivation body into each of the plurality of trenches, each passivation body partially filling a respective trench and including a lining along each of the sidewalls of the respective trench, the linings in each trench being spaced from one another with empty space;
forming a carrier layer at the first side of the wafer;
grinding the wafer from the second side to expose the bottom of each trench of the plurality of trenches;
forming a metal layer on a second side of the wafer;
removing the carrier layer; and
separating the die from the wafer.
9. A method of singulating a semiconductor die from a wafer, the method comprising:
at least one of etching or cutting a plurality of trenches into the wafer from a first side of the wafer, each trench including opposite sidewalls and extending through at least a majority of a depth of the wafer along an entire side of the die;
depositing a passivation body into each of the plurality of trenches, each passivation body partially filling a respective trench and including a lining along each of the sidewalls of the respective trench, the linings in each trench being spaced from one another with empty space;
forming an adhesive layer at the first side of the wafer, said adhesive layer filling said empty space of said plurality of trenches;
forming a carrier layer above the adhesive layer;
grinding the wafer from the second side to expose the bottom of each trench of the plurality of trenches;
forming a metal layer on a second side of the wafer;
removing the carrier layer by dissolving or deactivating the adhesive layer; and
separating the die from the wafer.
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The present application claims priority from U.S. Provisional Application No. 60/727,711, filed Oct. 18, 2005, which is incorporated in full herein by reference.
This invention relates to semiconductor device processing and more specifically relates to a novel process for singulating semiconductor dies from a wafer.
Semiconductor dies such as diodes, transistors and the like are commonly processed (formed) simultaneously in a large area wafer. Such wafers may be made of monocrystaline silicon or other materials, such as gallium nitride on a suitable substrate such as silicon or the like. After the processing steps are completed, the wafers are singulated, separating the die from the wafer. This “dicing,” separation or singulating operation is commonly carried out by sawing through the “streets” between the dies within the wafers.
Singulating the dies of the wafer, for example, by sawing the wafer along the streets after the wafer is complete, including metal layers on the back or front side, can be a time consuming and costly process. Further, the singulation process can damage portions of the dies, including the sides of the dies.
A method of singulating a semiconductor die from a wafer, including: etching or cutting several trenches into the wafer from a first side, such as a front surface, of the wafer, such that each trench extends through at least a majority of a depth of the wafer along an entire side of the die; depositing a passivation layer into the trenches to form a passivation plug on at least a bottom of the trenches; forming a carrier layer at the first side of the wafer; grinding the wafer from the back side to expose the bottom of each trench before the forming of the metal layer; forming a metal layer on a second side, such as a back surface, of the wafer; removing the carrier layer; and separating the die from the wafer.
Further an adhesive layer may be formed immediately beneath the carrier layer, such that the carrier layer is removed by dissolving or deactivating the adhesive layer.
Also, the metal layer on the second side may be a back metal layer. Dicing tape may be added directly over the metal layer on the second side before the removing of the carrier layer. The die may be separated by flexing the tape and/or by laser cutting the passivation plug.
A method of singulating the dies of the wafer will now be described with reference to
A mask layer is then deposited along the first side of the wafer and a portion of the mask is removed to leave mask deposits 13 and 14, thus exposing the top of the wafer 10 as an etch window so that a trench 20 may be etched.
Passivation coating 25 is then applied along the top surface of the wafer as shown in
The passivation plug 25A on or near the bottom of trench 20 protects the dies and the structures of the die, including the sides of the die of the wafer 10 during the grinding and polishing process. Also, passivation plug 25A may aid in stopping the individual dies from moving by providing an additional securing or reinforcing means. The thickness of the passivation plug 25A can be varied depending on the material used for the passivation layer 25, the thickness of the wafer, the radius of the wafer 10, and other such factors.
An adhesive layer 31 of the type that can be dissolved or whose adhesive effect can be neutralized, for example by radiation or by chemical means, may be used to adhere carrier layer 30 to the top surface of the wafer 10, as shown in
With the wafer 10 physically supported or reinforced by the carrier layer 30, as shown in
As shown in
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Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.
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